Health surveys consistently find that women have higher rates of illness, disability days, health services use, and medicine use than men. The principal goals of this research are to provide thorough explanatory analyses of sex differences in health and to define models for testing sex differences in both physical and mental health. Three general hypotheses about male-female differences in health are tested: (1) illness behavior (different propensities to perceive symptoms, evaluate them, and take curative actions), (2) acquired risks of illness and injury due to social roles, life styles, and stress, and (3) reporting behavior. As part of this research, we will examine some methodological features of health indicators and also analyze the daily dynamics of health events (asking how mood and special events trigger symptoms and health actions). The data source is the Health In Detroit Study, conducted in 1978 under a research grant (MH 29478) from the Center for Epidemiologic Studies. The study was designed specifically to explain sex differences in health. A probability sample of white adults in the Detroit metropolitan area was chosen. After an Initial Interview (n equals 714), respondents kept a Daily Health Record for six weeks. Each day they reported symptoms, restricted activity, medical/dental visits, medicines and treatments, communications with peers about symptoms, mood, and special events of the day. At the end of the diary period, a Termination Interview was conducted. The proposed grant will support comprehensive analysis of the Health In Detroit data. The research has theoretical and methodological significance for identifying (1) reasons for longstanding differences in the health of men and women, as reported in health surveys, (2) features of prospective reports, self-reports, comprehensive health indicators, and daily measures of health, and (3) factors which precipitate symptoms and which channel people into health services use and self-treatment.